1. Field of the Invention
Apparatuses and methods consistent with the present invention relate to plasma generating, and more particularly, to a microwave resonance plasma generating apparatus and a plasma processing system having the same, which is used for a semiconductor substrate processing for etching and removing a thin film from a substrate or depositing the thin film on the substrate.
2. Description of the Related Art
In recent years, as a need of high speed microprocessors and high recording density memories increases, an ultra large scale integrated (ULSI) circuit made of one semiconductor chip having many elements mounted thereon have been actively developed. To manufacture such a next generation ULSI circuit, it is necessary to process a 30 cm wafer having a design standard of less than 0.1 μm by using plasma. At this time, the plasma should have a high density of more than 1011 cm−3 and a large diameter of more than 40 cm at a low pressure of less than 50 mTorr. Particularly, to manufacture a large electronic device such as a flat panel display and a solar cell, the plasma should have a diameter of at least 1 m.
In order to embody the ULSI circuit technique, it requires that a high performance deposition and/or etching device is used during a manufacturing process of the semiconductor chip. As examples of the high performance deposition and/or etching device, a plasma etcher, a plasma sputtering system, a plasma enhanced chemical vapor deposition PECVD system and the like are well-known.
FIG. 1 is a schematic cross-sectional view illustrating an electron cyclotron resonance (ECR) plasma processing apparatus 10 that uses a microwave resonance phenomenon. The ECR plasma processing apparatus 10 is adapted for use in a plasma etcher, a plasma sputtering system, or a PECVD system.
As illustrated in FIG. 1, the ECR plasma processing apparatus 10 includes a magnetron 11, a waveguide 13, a horn antenna 14, a resonance channel 15, and an electromagnet 16.
The waveguide 13 propagates a microwave generated from the magnetron 11 to the horn antenna 14. The horn antenna 14 propagates the microwave transmitted thorough the waveguide 13 into the resonance channel 15, so that the microwave can form a resonance mode in the resonance channel 15.
The electromagnet 16 is disposed around the resonance channel 15 to form a magnetic field in a direction parallel to the propagation direction of the microwave, that is, a direction of Z, in the resonance channel 15.
The microwave moved into the resonance channel 15 transfers energy to electrons that gyro-motion about the magnetic field formed in the resonance channel 15 by the electromagnet 16. The electrons to which the energy is applied collide against a gas in the resonance channel 15 to ionize the gas and thus to form plasma.
Such a conventional ECR plasma processing apparatus 10 has an advantage that can obtain plasma of high density at a relatively low pressure by using a microwave having a high frequency of about 2.45 GHz. However, since the conventional ECR plasma processing apparatus 10 requires a magnetic field of about 875 Gauss for producing the plasma, it needs the electromagnet 16 that consumes much electric power. Further, the conventional ECR plasma processing apparatus 10 does not uniformly form the plasma.
Further, in order to maximize a plasma producing efficiency, the conventional ECR plasma processing apparatus 10 should be designed in an optimum ECR condition. Therefore, process conditions of the conventional ECR plasma processing apparatus 10 may not be freely selected, but restricted.
Also, the conventional ECR plasma processing apparatus 10 uses a plurality of parts including the waveguide 13, the horn antenna 14, the electromagnet 15, and the like. Accordingly, there is a problem that the structure may be complicated, the size may be enlarged, and the manufacturing cost may be increased.
In order to solve this problem, there has been provided a surface wave excitation microwave plasma processing apparatus 50 that uses an annular waveguide 53 having a plurality slots formed at an inner side surface thereof, as illustrated in FIG. 2. The apparatus 50 is disclosed in U.S. Pat. No. 5,487,875.
The microwave plasma processing apparatus 50 includes a microwave generating unit (not illustrated) such as a magnetron, a waveguide 53, and a plasma generating chamber 51.
As illustrated in FIGS. 3 through 5, a microwave 73 generated from the microwave generating unit is guided to the waveguide 53, and is then distributed left and right by a distributing block 71 to propagate in the waveguide 53 having a wavelength longer than a free space.
Then, the microwave 73 is introduced into the plasma generating chamber 51 as a leaky wave 75 through slots 72 formed at intervals of ½ or ¼ of the wavelength and a dielectric body 52. The leaky wave 75 generates plasma 77 in the vicinity of the slots 72.
Also, the microwave incident at an angle of more than Brewster angle to a straight line vertical to a surface of the dielectric body 52 is total-reflected at the surface of the dielectric body 52, and is propagated as a surface wave 76 inside the dielectric body 52. A leaky electric field of the surface wave 76 also produces plasma 77′.
The produced plasma 77 and 77′ excites a gas supplied into a process chamber 61 through a gas injection tube 65, and the excited gas processes a surface of a substrate 62 disposed on a substrate holder 63.
This microwave plasma processing apparatus 50 as described above has an advantage that can obtain the plasma of high density with a relatively simplified structure compared with the ECR plasma generating apparatus 10 including the electromagnet and the like to increase the manufacturing cost and the size.
However, the microwave plasma processing apparatus 50 is configured, such that the microwave 73 generated from the microwave generating unit is propagated into the plasma generating chamber 51 through the slots 72 along the annular waveguide 53. Accordingly, the microwave propagated into the plasma generating chamber 51 has different intensity according to a position of slots due to attenuating characteristic of wave. As a result, the plasma is unevenly formed, and the plasma producing efficiency is deteriorated.
Therefore, what is needed is a microwave plasma processing apparatus capable of obtaining a sufficient plasma producing efficiency while having a relatively simplified structure so as not to increase the size and the manufacturing cost.